Indication of serving cell communication quality to target cell during mobility

ABSTRACT

A method and apparatus for an indication of serving cell communication quality to a target cell during mobility in a wireless communication system is provided. A wireless device, which keeps communicating with a source node while initiating a mobility from the source node to a target node, transmits, to the target node, information related to a communication quality of the source node.

TECHNICAL FIELD

The present disclosure relates to an indication of serving cellcommunication quality to a target cell during mobility.

BACKGROUND

3rd generation partnership project (3GPP) long-term evolution (LTE) is atechnology for enabling high-speed packet communications. Many schemeshave been proposed for the LTE objective including those that aim toreduce user and provider costs, improve service quality, and expand andimprove coverage and system capacity. The 3GPP LTE requires reduced costper bit, increased service availability, flexible use of a frequencyband, a simple structure, an open interface, and adequate powerconsumption of a terminal as an upper-level requirement.

Work has started in international telecommunication union (ITU) and 3GPPto develop requirements and specifications for new radio (NR) systems.3GPP has to identify and develop the technology components needed forsuccessfully standardizing the new RAT timely satisfying both the urgentmarket needs, and the more long-term requirements set forth by the ITUradio communication sector (ITU-R) international mobiletelecommunications (IMT)-2020 process. Further, the NR should be able touse any spectrum band ranging at least up to 100 GHz that may be madeavailable for wireless communications even in a more distant future.

The NR targets a single technical framework addressing all usagescenarios, requirements and deployment scenarios including enhancedmobile broadband (eMBB), massive machine-type-communications (mMTC),ultra-reliable and low latency communications (URLLC), etc. The NR shallbe inherently forward compatible.

Network controlled mobility in 5G NR applies to user equipments (UEs) ina connected state (e.g., RRC_CONNECTED) and is categorized into twotypes of mobility: cell level mobility and beam level mobility. Celllevel mobility requires explicit radio resource control (RRC) signalingto be triggered, i.e., handover.

SUMMARY

For enhancement of mobility, e.g., handover, various schemes have beenstudied and/or discussed. For example, for a user equipment (UE) thathas radio capabilities of concurrent transmissions and receptions withat least two cells, maintaining connectivity with both source cell andtarget cell during mobility may be addressed to increase mobilityperformance. For this, proper control by a target node should berequired.

In an aspect, a method for a wireless device in a wireless communicationsystem is provided. The method includes keeping communicating with asource node while initiating a mobility from the source node to a targetnode, and transmitting, to the target node, information related to acommunication quality of the source node.

In another aspect, an apparatus for implementing the above method isprovided.

The present disclosure can have various advantageous effects.

For example, upon receiving information related to the communicationquality of the source node and/or source cell from the wireless device,the target node can decide whether to allow the source node keepscommunication with the wireless device or to request stoppingimmediately communication with the wireless device.

For example, the target node can properly control source cellconnectivity during and/or after mobility.

For example, overall communication performance can be enhanced while thetarget node is properly utilized for the wireless device.

Advantageous effects which can be obtained through specific embodimentsof the present disclosure are not limited to the advantageous effectslisted above. For example, there may be a variety of technical effectsthat a person having ordinary skill in the related art can understandand/or derive from the present disclosure. Accordingly, the specificeffects of the present disclosure are not limited to those explicitlydescribed herein, but may include various effects that may be understoodor derived from the technical features of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a communication system to whichimplementations of the present disclosure is applied.

FIG. 2 shows an example of wireless devices to which implementations ofthe present disclosure is applied.

FIG. 3 shows an example of a wireless device to which implementations ofthe present disclosure is applied.

FIG. 4 shows another example of wireless devices to whichimplementations of the present disclosure is applied.

FIG. 5 shows an example of UE to which implementations of the presentdisclosure is applied.

FIGS. 6 and 7 show an example of protocol stacks in a 3GPP basedwireless communication system to which implementations of the presentdisclosure is applied.

FIG. 8 shows a frame structure in a 3GPP based wireless communicationsystem to which implementations of the present disclosure is applied.

FIG. 9 shows a data flow example in the 3GPP NR system to whichimplementations of the present disclosure is applied.

FIG. 10 shows an example of inter-gNB handover procedures to whichimplementations of the present disclosure is applied.

FIG. 11 shows an example of a protocol stack for DAPS based handover towhich implementations of the present disclosure is applied.

FIG. 12 shows another example of a protocol stack for DAPS basedhandover to which implementations of the present disclosure is applied.

FIG. 13 shows another example of a protocol stack for DAPS basedhandover to which implementations of the present disclosure is applied.

FIG. 14 shows an example of a method for a wireless device to whichimplementations of the present disclosure is applied.

DETAILED DESCRIPTION

The following techniques, apparatuses, and systems may be applied to avariety of wireless multiple access systems. Examples of the multipleaccess systems include a code division multiple access (CDMA) system, afrequency division multiple access (FDMA) system, a time divisionmultiple access (TDMA) system, an orthogonal frequency division multipleaccess (OFDMA) system, a single carrier frequency division multipleaccess (SC-FDMA) system, and a multicarrier frequency division multipleaccess (MC-FDMA) system. CDMA may be embodied through radio technologysuch as universal terrestrial radio access (UTRA) or CDMA2000. TDMA maybe embodied through radio technology such as global system for mobilecommunications (GSM), general packet radio service (GPRS), or enhanceddata rates for GSM evolution (EDGE). OFDMA may be embodied through radiotechnology such as institute of electrical and electronics engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or evolved UTRA(E-UTRA). UTRA is a part of a universal mobile telecommunications system(UMTS). 3rd generation partnership project (3GPP) long term evolution(LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employsOFDMA in DL and SC-FDMA in UL. LTE-advanced (LTE-A) is an evolvedversion of 3GPP LTE.

For convenience of description, implementations of the presentdisclosure are mainly described in regards to a 3GPP based wirelesscommunication system. However, the technical features of the presentdisclosure are not limited thereto. For example, although the followingdetailed description is given based on a mobile communication systemcorresponding to a 3GPP based wireless communication system, aspects ofthe present disclosure that are not limited to 3GPP based wirelesscommunication system are applicable to other mobile communicationsystems.

For terms and technologies which are not specifically described amongthe terms of and technologies employed in the present disclosure, thewireless communication standard documents published before the presentdisclosure may be referenced.

In the present disclosure, “A or B” may mean “only A”, “only B”, or“both A and B”. In other words, “A or B” in the present disclosure maybe interpreted as “A and/or B”. For example, “A, B or C” in the presentdisclosure may mean “only A”, “only B”, “only C”, or “any combination ofA, B and C”.

In the present disclosure, slash (/) or comma (,) may mean “and/or”. Forexample, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “onlyA”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, Bor C”.

In the present disclosure, “at least one of A and B” may mean “only A”,“only B” or “both A and B”. In addition, the expression “at least one ofA or B” or “at least one of A and/or B” in the present disclosure may beinterpreted as same as “at least one of A and B”.

In addition, in the present disclosure, “at least one of A, B and C” maymean “only A”, “only B”, “only C”, or “any combination of A, B and C”.In addition, “at least one of A, B or C” or “at least one of A, B and/orC” may mean “at least one of A, B and C”.

Also, parentheses used in the present disclosure may mean “for example”.In detail, when it is shown as “control information (PDCCH)”, “PDCCH”may be proposed as an example of “control information”. In other words,“control information” in the present disclosure is not limited to“PDCCH”, and “PDDCH” may be proposed as an example of “controlinformation”. In addition, even when shown as “control information(i.e., PDCCH)”, “PDCCH” may be proposed as an example of “controlinformation”.

Technical features that are separately described in one drawing in thepresent disclosure may be implemented separately or simultaneously.

Although not limited thereto, various descriptions, functions,procedures, suggestions, methods and/or operational flowcharts of thepresent disclosure disclosed herein can be applied to various fieldsrequiring wireless communication and/or connection (e.g., 5G) betweendevices.

Hereinafter, the present disclosure will be described in more detailwith reference to drawings. The same reference numerals in the followingdrawings and/or descriptions may refer to the same and/or correspondinghardware blocks, software blocks, and/or functional blocks unlessotherwise indicated.

FIG. 1 shows an example of a communication system to whichimplementations of the present disclosure is applied.

The 5G usage scenarios shown in FIG. 1 are only exemplary, and thetechnical features of the present disclosure can be applied to other 5Gusage scenarios which are not shown in FIG. 1.

Three main requirement categories for 5G include (1) a category ofenhanced mobile broadband (eMBB), (2) a category of massive machine typecommunication (mMTC), and (3) a category of ultra-reliable and lowlatency communications (URLLC).

Partial use cases may require a plurality of categories for optimizationand other use cases may focus only upon one key performance indicator(KPI). 5G supports such various use cases using a flexible and reliablemethod.

eMBB far surpasses basic mobile Internet access and covers abundantbidirectional work and media and entertainment applications in cloud andaugmented reality. Data is one of 5G core motive forces and, in a 5Gera, a dedicated voice service may not be provided for the first time.In 5G, it is expected that voice will be simply processed as anapplication program using data connection provided by a communicationsystem. Main causes for increased traffic volume are due to an increasein the size of content and an increase in the number of applicationsrequiring high data transmission rate. A streaming service (of audio andvideo), conversational video, and mobile Internet access will be morewidely used as more devices are connected to the Internet. These manyapplication programs require connectivity of an always turned-on statein order to push real-time information and alarm for users. Cloudstorage and applications are rapidly increasing in a mobilecommunication platform and may be applied to both work andentertainment. The cloud storage is a special use case which acceleratesgrowth of uplink data transmission rate. 5G is also used for remote workof cloud. When a tactile interface is used, 5G demands much lowerend-to-end latency to maintain user good experience. Entertainment, forexample, cloud gaming and video streaming, is another core element whichincreases demand for mobile broadband capability. Entertainment isessential for a smartphone and a tablet in any place including highmobility environments such as a train, a vehicle, and an airplane. Otheruse cases are augmented reality for entertainment and informationsearch. In this case, the augmented reality requires very low latencyand instantaneous data volume.

In addition, one of the most expected 5G use cases relates a functioncapable of smoothly connecting embedded sensors in all fields, i.e.,mMTC. It is expected that the number of potential Internet-of-things(IoT) devices will reach 204 hundred million up to the year of 2020. Anindustrial IoT is one of categories of performing a main role enabling asmart city, asset tracking, smart utility, agriculture, and securityinfrastructure through 5G.

URLLC includes a new service that will change industry through remotecontrol of main infrastructure and an ultra-reliable/availablelow-latency link such as a self-driving vehicle. A level of reliabilityand latency is essential to control a smart grid, automatize industry,achieve robotics, and control and adjust a drone.

5G is a means of providing streaming evaluated as a few hundred megabitsper second to gigabits per second and may complement fiber-to-the-home(FTTH) and cable-based broadband (or DOCSIS). Such fast speed is neededto deliver TV in resolution of 4K or more (6K, 8K, and more), as well asvirtual reality and augmented reality. Virtual reality (VR) andaugmented reality (AR) applications include almost immersive sportsgames. A specific application program may require a special networkconfiguration. For example, for VR games, gaming companies need toincorporate a core server into an edge network server of a networkoperator in order to minimize latency.

Automotive is expected to be a new important motivated force in 5Gtogether with many use cases for mobile communication for vehicles. Forexample, entertainment for passengers requires high simultaneouscapacity and mobile broadband with high mobility. This is because futureusers continue to expect connection of high quality regardless of theirlocations and speeds. Another use case of an automotive field is an ARdashboard. The AR dashboard causes a driver to identify an object in thedark in addition to an object seen from a front window and displays adistance from the object and a movement of the object by overlappinginformation talking to the driver. In the future, a wireless moduleenables communication between vehicles, information exchange between avehicle and supporting infrastructure, and information exchange betweena vehicle and other connected devices (e.g., devices accompanied by apedestrian). A safety system guides alternative courses of a behavior sothat a driver may drive more safely drive, thereby lowering the dangerof an accident. The next stage will be a remotely controlled orself-driven vehicle. This requires very high reliability and very fastcommunication between different self-driven vehicles and between avehicle and infrastructure. In the future, a self-driven vehicle willperform all driving activities and a driver will focus only uponabnormal traffic that the vehicle cannot identify. Technicalrequirements of a self-driven vehicle demand ultra-low latency andultra-high reliability so that traffic safety is increased to a levelthat cannot be achieved by human being.

A smart city and a smart home/building mentioned as a smart society willbe embedded in a high-density wireless sensor network. A distributednetwork of an intelligent sensor will identify conditions for costs andenergy-efficient maintenance of a city or a home Similar configurationsmay be performed for respective households. All of temperature sensors,window and heating controllers, burglar alarms, and home appliances arewirelessly connected. Many of these sensors are typically low in datatransmission rate, power, and cost. However, real-time HD video may bedemanded by a specific type of device to perform monitoring.

Consumption and distribution of energy including heat or gas isdistributed at a higher level so that automated control of thedistribution sensor network is demanded. The smart grid collectsinformation and connects the sensors to each other using digitalinformation and communication technology so as to act according to thecollected information. Since this information may include behaviors of asupply company and a consumer, the smart grid may improve distributionof fuels such as electricity by a method having efficiency, reliability,economic feasibility, production sustainability, and automation. Thesmart grid may also be regarded as another sensor network having lowlatency.

Mission critical application (e.g., e-health) is one of 5G usescenarios. A health part contains many application programs capable ofenjoying benefit of mobile communication. A communication system maysupport remote treatment that provides clinical treatment in a farawayplace. Remote treatment may aid in reducing a barrier against distanceand improve access to medical services that cannot be continuouslyavailable in a faraway rural area. Remote treatment is also used toperform important treatment and save lives in an emergency situation.The wireless sensor network based on mobile communication may provideremote monitoring and sensors for parameters such as heart rate andblood pressure.

Wireless and mobile communication gradually becomes important in thefield of an industrial application. Wiring is high in installation andmaintenance cost. Therefore, a possibility of replacing a cable withreconstructible wireless links is an attractive opportunity in manyindustrial fields. However, in order to achieve this replacement, it isnecessary for wireless connection to be established with latency,reliability, and capacity similar to those of the cable and managementof wireless connection needs to be simplified. Low latency and a verylow error probability are new requirements when connection to 5G isneeded.

Logistics and freight tracking are important use cases for mobilecommunication that enables inventory and package tracking anywhere usinga location-based information system. The use cases of logistics andfreight typically demand low data rate but require location informationwith a wide range and reliability.

Referring to FIG. 1, the communication system 1 includes wirelessdevices 100 a to 100 f, base stations (BSs) 200, and a network 300.Although FIG. 1 illustrates a 5G network as an example of the network ofthe communication system 1, the implementations of the presentdisclosure are not limited to the 5G system, and can be applied to thefuture communication system beyond the 5G system.

The BSs 200 and the network 300 may be implemented as wireless devicesand a specific wireless device may operate as a BS/network node withrespect to other wireless devices.

The wireless devices 100 a to 100 f represent devices performingcommunication using radio access technology (RAT) (e.g., 5G new RAT(NR)) or LTE) and may be referred to as communication/radio/5G devices.The wireless devices 100 a to 100 f may include, without being limitedto, a robot 100 a, vehicles 100 b-1 and 100 b-2, an extended reality(XR) device 100 c, a hand-held device 100 d, a home appliance 100 e, anIoT device 100 f, and an artificial intelligence (AI) device/server 400.For example, the vehicles may include a vehicle having a wirelesscommunication function, an autonomous driving vehicle, and a vehiclecapable of performing communication between vehicles. The vehicles mayinclude an unmanned aerial vehicle (UAV) (e.g., a drone). The XR devicemay include an AR/VR/Mixed Reality (MR) device and may be implemented inthe form of a head-mounted device (HMD), a head-up display (HUD) mountedin a vehicle, a television, a smartphone, a computer, a wearable device,a home appliance device, a digital signage, a vehicle, a robot, etc. Thehand-held device may include a smartphone, a smartpad, a wearable device(e.g., a smartwatch or a smartglasses), and a computer (e.g., anotebook). The home appliance may include a TV, a refrigerator, and awashing machine. The IoT device may include a sensor and a smartmeter.

In the present disclosure, the wireless devices 100 a to 100 f may becalled user equipments (UEs). A UE may include, for example, a cellularphone, a smartphone, a laptop computer, a digital broadcast terminal, apersonal digital assistant (PDA), a portable multimedia player (PMP), anavigation system, a slate personal computer (PC), a tablet PC, anultrabook, a vehicle, a vehicle having an autonomous traveling function,a connected car, an UAV, an AI module, a robot, an AR device, a VRdevice, an MR device, a hologram device, a public safety device, an MTCdevice, an IoT device, a medical device, a FinTech device (or afinancial device), a security device, a weather/environment device, adevice related to a 5G service, or a device related to a fourthindustrial revolution field.

The UAV may be, for example, an aircraft aviated by a wireless controlsignal without a human being onboard.

The VR device may include, for example, a device for implementing anobject or a background of the virtual world. The AR device may include,for example, a device implemented by connecting an object or abackground of the virtual world to an object or a background of the realworld. The MR device may include, for example, a device implemented bymerging an object or a background of the virtual world into an object ora background of the real world. The hologram device may include, forexample, a device for implementing a stereoscopic image of 360 degreesby recording and reproducing stereoscopic information, using aninterference phenomenon of light generated when two laser lights calledholography meet.

The public safety device may include, for example, an image relay deviceor an image device that is wearable on the body of a user.

The MTC device and the IoT device may be, for example, devices that donot require direct human intervention or manipulation. For example, theMTC device and the IoT device may include smartmeters, vending machines,thermometers, smartbulbs, door locks, or various sensors.

The medical device may be, for example, a device used for the purpose ofdiagnosing, treating, relieving, curing, or preventing disease. Forexample, the medical device may be a device used for the purpose ofdiagnosing, treating, relieving, or correcting injury or impairment. Forexample, the medical device may be a device used for the purpose ofinspecting, replacing, or modifying a structure or a function. Forexample, the medical device may be a device used for the purpose ofadjusting pregnancy. For example, the medical device may include adevice for treatment, a device for operation, a device for (in vitro)diagnosis, a hearing aid, or a device for procedure.

The security device may be, for example, a device installed to prevent adanger that may arise and to maintain safety. For example, the securitydevice may be a camera, a closed-circuit TV (CCTV), a recorder, or ablack box.

The FinTech device may be, for example, a device capable of providing afinancial service such as mobile payment. For example, the FinTechdevice may include a payment device or a point of sales (POS) system.

The weather/environment device may include, for example, a device formonitoring or predicting a weather/environment.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR)network, and a beyond-5G network. Although the wireless devices 100 a to100 f may communicate with each other through the BSs 200/network 300,the wireless devices 100 a to 100 f may perform direct communication(e.g., sidelink communication) with each other without passing throughthe BSs 200/network 300. For example, the vehicles 100 b-1 and 100 b-2may perform direct communication (e.g., vehicle-to-vehicle(V2V)/vehicle-to-everything (V2X) communication). The IoT device (e.g.,a sensor) may perform direct communication with other IoT devices (e.g.,sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b and 150 c may beestablished between the wireless devices 100 a to 100 f and/or betweenwireless device 100 a to 100 f and BS 200 and/or between BSs 200.Herein, the wireless communication/connections may be establishedthrough various RATs (e.g., 5G NR) such as uplink/downlink communication150 a, sidelink communication (or device-to-device (D2D) communication)150 b, inter-base station communication 150 c (e.g., relay, integratedaccess and backhaul (IAB)), etc. The wireless devices 100 a to 100 f andthe BSs 200/the wireless devices 100 a to 100 f may transmit/receiveradio signals to/from each other through the wirelesscommunication/connections 150 a, 150 b and 150 c. For example, thewireless communication/connections 150 a, 150 b and 150 c maytransmit/receive signals through various physical channels. To this end,at least a part of various configuration information configuringprocesses, various signal processing processes (e.g., channelencoding/decoding, modulation/demodulation, and resourcemapping/de-mapping), and resource allocating processes, fortransmitting/receiving radio signals, may be performed based on thevarious proposals of the present disclosure.

FIG. 2 shows an example of wireless devices to which implementations ofthe present disclosure is applied.

Referring to FIG. 2, a first wireless device 100 and a second wirelessdevice 200 may transmit/receive radio signals to/from an external devicethrough a variety of RATs (e.g., LTE and NR). In FIG. 2, {the firstwireless device 100 and the second wireless device 200} may correspondto at least one of {the wireless device 100 a to 100 f and the BS 200},{the wireless device 100 a to 100 f and the wireless device 100 a to 100f} and/or {the BS 200 and the BS 200} of FIG. 1.

The first wireless device 100 may include one or more processors 102 andone or more memories 104 and additionally further include one or moretransceivers 106 and/or one or more antennas 108. The processor(s) 102may control the memory(s) 104 and/or the transceiver(s) 106 and may beconfigured to implement the descriptions, functions, procedures,suggestions, methods and/or operational flowcharts described in thepresent disclosure. For example, the processor(s) 102 may processinformation within the memory(s) 104 to generate firstinformation/signals and then transmit radio signals including the firstinformation/signals through the transceiver(s) 106. The processor(s) 102may receive radio signals including second information/signals throughthe transceiver(s) 106 and then store information obtained by processingthe second information/signals in the memory(s) 104. The memory(s) 104may be connected to the processor(s) 102 and may store a variety ofinformation related to operations of the processor(s) 102. For example,the memory(s) 104 may store software code including commands forperforming a part or the entirety of processes controlled by theprocessor(s) 102 or for performing the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts describedin the present disclosure. Herein, the processor(s) 102 and thememory(s) 104 may be a part of a communication modem/circuit/chipdesigned to implement RAT (e.g., LTE or NR). The transceiver(s) 106 maybe connected to the processor(s) 102 and transmit and/or receive radiosignals through one or more antennas 108. Each of the transceiver(s) 106may include a transmitter and/or a receiver. The transceiver(s) 106 maybe interchangeably used with radio frequency (RF) unit(s). In thepresent disclosure, the first wireless device 100 may represent acommunication modem/circuit/chip.

The second wireless device 200 may include one or more processors 202and one or more memories 204 and additionally further include one ormore transceivers 206 and/or one or more antennas 208. The processor(s)202 may control the memory(s) 204 and/or the transceiver(s) 206 and maybe configured to implement the descriptions, functions, procedures,suggestions, methods and/or operational flowcharts described in thepresent disclosure. For example, the processor(s) 202 may processinformation within the memory(s) 204 to generate thirdinformation/signals and then transmit radio signals including the thirdinformation/signals through the transceiver(s) 206. The processor(s) 202may receive radio signals including fourth information/signals throughthe transceiver(s) 106 and then store information obtained by processingthe fourth information/signals in the memory(s) 204. The memory(s) 204may be connected to the processor(s) 202 and may store a variety ofinformation related to operations of the processor(s) 202. For example,the memory(s) 204 may store software code including commands forperforming a part or the entirety of processes controlled by theprocessor(s) 202 or for performing the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts describedin the present disclosure. Herein, the processor(s) 202 and thememory(s) 204 may be a part of a communication modem/circuit/chipdesigned to implement RAT (e.g., LTE or NR). The transceiver(s) 206 maybe connected to the processor(s) 202 and transmit and/or receive radiosignals through one or more antennas 208. Each of the transceiver(s) 206may include a transmitter and/or a receiver. The transceiver(s) 206 maybe interchangeably used with RF unit(s). In the present disclosure, thesecond wireless device 200 may represent a communicationmodem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 willbe described more specifically. One or more protocol layers may beimplemented by, without being limited to, one or more processors 102 and202. For example, the one or more processors 102 and 202 may implementone or more layers (e.g., functional layers such as physical (PHY)layer, media access control (MAC) layer, radio link control (RLC) layer,packet data convergence protocol (PDCP) layer, radio resource control(RRC) layer, and service data adaptation protocol (SDAP) layer). The oneor more processors 102 and 202 may generate one or more protocol dataunits (PDUs) and/or one or more service data unit (SDUs) according tothe descriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure. The one ormore processors 102 and 202 may generate messages, control information,data, or information according to the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. The one or more processors 102 and 202 maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure and providethe generated signals to the one or more transceivers 106 and 206. Theone or more processors 102 and 202 may receive the signals (e.g.,baseband signals) from the one or more transceivers 106 and 206 andacquire the PDUs, SDUs, messages, control information, data, orinformation according to the descriptions, functions, procedures,suggestions, methods and/or operational flowcharts disclosed in thepresent disclosure.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. As an example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. descriptions, functions, procedures,suggestions, methods and/or operational flowcharts disclosed in thepresent disclosure may be implemented using firmware or software and thefirmware or software may be configured to include the modules,procedures, or functions. Firmware or software configured to perform thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure may beincluded in the one or more processors 102 and 202 or stored in the oneor more memories 104 and 204 so as to be driven by the one or moreprocessors 102 and 202. The descriptions, functions, procedures,suggestions, methods and/or operational flowcharts disclosed in thepresent disclosure may be implemented using firmware or software in theform of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured by read-onlymemories (ROMs), random access memories (RAMs), electrically erasableprogrammable read-only memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure, to one ormore other devices. The one or more transceivers 106 and 206 may receiveuser data, control information, and/or radio signals/channels, mentionedin the descriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure, from one ormore other devices. For example, the one or more transceivers 106 and206 may be connected to the one or more processors 102 and 202 andtransmit and receive radio signals. For example, the one or moreprocessors 102 and 202 may perform control so that the one or moretransceivers 106 and 206 may transmit user data, control information, orradio signals to one or more other devices. The one or more processors102 and 202 may perform control so that the one or more transceivers 106and 206 may receive user data, control information, or radio signalsfrom one or more other devices.

The one or more transceivers 106 and 206 may be connected to the one ormore antennas 108 and 208 and the one or more transceivers 106 and 206may be configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure, through theone or more antennas 108 and 208. In the present disclosure, the one ormore antennas may be a plurality of physical antennas or a plurality oflogical antennas (e.g., antenna ports).

The one or more transceivers 106 and 206 may convert received radiosignals/channels, etc., from RF band signals into baseband signals inorder to process received user data, control information, radiosignals/channels, etc., using the one or more processors 102 and 202.The one or more transceivers 106 and 206 may convert the user data,control information, radio signals/channels, etc., processed using theone or more processors 102 and 202 from the base band signals into theRF band signals. To this end, the one or more transceivers 106 and 206may include (analog) oscillators and/or filters. For example, thetransceivers 106 and 206 can up-convert OFDM baseband signals to acarrier frequency by their (analog) oscillators and/or filters under thecontrol of the processors 102 and 202 and transmit the up-converted OFDMsignals at the carrier frequency. The transceivers 106 and 206 mayreceive OFDM signals at a carrier frequency and down-convert the OFDMsignals into OFDM baseband signals by their (analog) oscillators and/orfilters under the control of the transceivers 102 and 202.

In the implementations of the present disclosure, a UE may operate as atransmitting device in uplink (UL) and as a receiving device in downlink(DL). In the implementations of the present disclosure, a BS may operateas a receiving device in UL and as a transmitting device in DL.Hereinafter, for convenience of description, it is mainly assumed thatthe first wireless device 100 acts as the UE, and the second wirelessdevice 200 acts as the BS. For example, the processor(s) 102 connectedto, mounted on or launched in the first wireless device 100 may beconfigured to perform the UE behavior according to an implementation ofthe present disclosure or control the transceiver(s) 106 to perform theUE behavior according to an implementation of the present disclosure.The processor(s) 202 connected to, mounted on or launched in the secondwireless device 200 may be configured to perform the BS behavioraccording to an implementation of the present disclosure or control thetransceiver(s) 206 to perform the BS behavior according to animplementation of the present disclosure.

In the present disclosure, a BS is also referred to as a node B (NB), aneNode B (eNB), or a gNB.

FIG. 3 shows an example of a wireless device to which implementations ofthe present disclosure is applied

The wireless device may be implemented in various forms according to ause-case/service (refer to FIG. 1).

Referring to FIG. 3, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 2 and may be configured by variouselements, components, units/portions, and/or modules. For example, eachof the wireless devices 100 and 200 may include a communication unit110, a control unit 120, a memory unit 130, and additional components140. The communication unit 110 may include a communication circuit 112and transceiver(s) 114. For example, the communication circuit 112 mayinclude the one or more processors 102 and 202 of FIG. 2 and/or the oneor more memories 104 and 204 of FIG. 2. For example, the transceiver(s)114 may include the one or more transceivers 106 and 206 of FIG. 2and/or the one or more antennas 108 and 208 of FIG. 2. The control unit120 is electrically connected to the communication unit 110, the memory130, and the additional components 140 and controls overall operation ofeach of the wireless devices 100 and 200. For example, the control unit120 may control an electric/mechanical operation of each of the wirelessdevices 100 and 200 based on programs/code/commands/information storedin the memory unit 130. The control unit 120 may transmit theinformation stored in the memory unit 130 to the exterior (e.g., othercommunication devices) via the communication unit 110 through awireless/wired interface or store, in the memory unit 130, informationreceived through the wireless/wired interface from the exterior (e.g.,other communication devices) via the communication unit 110.

The additional components 140 may be variously configured according totypes of the wireless devices 100 and 200. For example, the additionalcomponents 140 may include at least one of a power unit/battery,input/output (I/O) unit (e.g., audio I/O port, video I/O port), adriving unit, and a computing unit. The wireless devices 100 and 200 maybe implemented in the form of, without being limited to, the robot (100a of FIG. 1), the vehicles (100 b-1 and 100 b-2 of FIG. 1), the XRdevice (100 c of FIG. 1), the hand-held device (100 d of FIG. 1), thehome appliance (100 e of FIG. 1), the IoT device (100 f of FIG. 1), adigital broadcast terminal, a hologram device, a public safety device,an MTC device, a medicine device, a FinTech device (or a financedevice), a security device, a climate/environment device, the AIserver/device (400 of FIG. 1), the BSs (200 of FIG. 1), a network node,etc. The wireless devices 100 and 200 may be used in a mobile or fixedplace according to a use-example/service.

In FIG. 3, the entirety of the various elements, components,units/portions, and/or modules in the wireless devices 100 and 200 maybe connected to each other through a wired interface or at least a partthereof may be wirelessly connected through the communication unit 110.For example, in each of the wireless devices 100 and 200, the controlunit 120 and the communication unit 110 may be connected by wire and thecontrol unit 120 and first units (e.g., 130 and 140) may be wirelesslyconnected through the communication unit 110. Each element, component,unit/portion, and/or module within the wireless devices 100 and 200 mayfurther include one or more elements. For example, the control unit 120may be configured by a set of one or more processors. As an example, thecontrol unit 120 may be configured by a set of a communication controlprocessor, an application processor (AP), an electronic control unit(ECU), a graphical processing unit, and a memory control processor. Asanother example, the memory 130 may be configured by a RAM, a DRAM, aROM, a flash memory, a volatile memory, a non-volatile memory, and/or acombination thereof.

FIG. 4 shows another example of wireless devices to whichimplementations of the present disclosure is applied.

Referring to FIG. 4, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 2 and may be configured by variouselements, components, units/portions, and/or modules.

The first wireless device 100 may include at least one transceiver, suchas a transceiver 106, and at least one processing chip, such as aprocessing chip 101. The processing chip 101 may include at least oneprocessor, such a processor 102, and at least one memory, such as amemory 104. The memory 104 may be operably connectable to the processor102. The memory 104 may store various types of information and/orinstructions. The memory 104 may store a software code 105 whichimplements instructions that, when executed by the processor 102,perform the descriptions, functions, procedures, suggestions, methodsand/or operational flowcharts disclosed in the present disclosure. Forexample, the software code 105 may implement instructions that, whenexecuted by the processor 102, perform the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. For example, the software code 105 maycontrol the processor 102 to perform one or more protocols. For example,the software code 105 may control the processor 102 may perform one ormore layers of the radio interface protocol.

The second wireless device 200 may include at least one transceiver,such as a transceiver 206, and at least one processing chip, such as aprocessing chip 201. The processing chip 201 may include at least oneprocessor, such a processor 202, and at least one memory, such as amemory 204. The memory 204 may be operably connectable to the processor202. The memory 204 may store various types of information and/orinstructions. The memory 204 may store a software code 205 whichimplements instructions that, when executed by the processor 202,perform the descriptions, functions, procedures, suggestions, methodsand/or operational flowcharts disclosed in the present disclosure. Forexample, the software code 205 may implement instructions that, whenexecuted by the processor 202, perform the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. For example, the software code 205 maycontrol the processor 202 to perform one or more protocols. For example,the software code 205 may control the processor 202 may perform one ormore layers of the radio interface protocol.

FIG. 5 shows an example of UE to which implementations of the presentdisclosure is applied.

Referring to FIG. 5, a UE 100 may correspond to the first wirelessdevice 100 of FIG. 2 and/or the first wireless device 100 of FIG. 4.

A UE 100 includes a processor 102, a memory 104, a transceiver 106, oneor more antennas 108, a power management module 110, a battery 1112, adisplay 114, a keypad 116, a subscriber identification module (SIM) card118, a speaker 120, and a microphone 122.

The processor 102 may be configured to implement the descriptions,functions, procedures, suggestions, methods and/or operationalflowcharts disclosed in the present disclosure. The processor 102 may beconfigured to control one or more other components of the UE 100 toimplement the descriptions, functions, procedures, suggestions, methodsand/or operational flowcharts disclosed in the present disclosure.Layers of the radio interface protocol may be implemented in theprocessor 102. The processor 102 may include ASIC, other chipset, logiccircuit and/or data processing device. The processor 102 may be anapplication processor. The processor 102 may include at least one of adigital signal processor (DSP), a central processing unit (CPU), agraphics processing unit (GPU), a modem (modulator and demodulator). Anexample of the processor 102 may be found in SNAPDRAGON™ series ofprocessors made by Qualcomm®, EXYNOS™ series of processors made bySamsung®, A series of processors made by Apple®, HELIO™ series ofprocessors made by MediaTek®, ATOM™ series of processors made by Intel®or a corresponding next generation processor.

The memory 104 is operatively coupled with the processor 102 and storesa variety of information to operate the processor 102. The memory 104may include ROM, RAM, flash memory, memory card, storage medium and/orother storage device. When the embodiments are implemented in software,the techniques described herein can be implemented with modules (e.g.,procedures, functions, etc.) that perform the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. The modules can be stored in the memory 104and executed by the processor 102. The memory 104 can be implementedwithin the processor 102 or external to the processor 102 in which casethose can be communicatively coupled to the processor 102 via variousmeans as is known in the art.

The transceiver 106 is operatively coupled with the processor 102, andtransmits and/or receives a radio signal. The transceiver 106 includes atransmitter and a receiver. The transceiver 106 may include basebandcircuitry to process radio frequency signals. The transceiver 106controls the one or more antennas 108 to transmit and/or receive a radiosignal.

The power management module 110 manages power for the processor 102and/or the transceiver 106. The battery 112 supplies power to the powermanagement module 110.

The display 114 outputs results processed by the processor 102. Thekeypad 116 receives inputs to be used by the processor 102. The keypad16 may be shown on the display 114.

The SIM card 118 is an integrated circuit that is intended to securelystore the international mobile subscriber identity (IMSI) number and itsrelated key, which are used to identify and authenticate subscribers onmobile telephony devices (such as mobile phones and computers). It isalso possible to store contact information on many SIM cards.

The speaker 120 outputs sound-related results processed by the processor102. The microphone 122 receives sound-related inputs to be used by theprocessor 102.

FIGS. 6 and 7 show an example of protocol stacks in a 3GPP basedwireless communication system to which implementations of the presentdisclosure is applied.

In particular, FIG. 6 illustrates an example of a radio interface userplane protocol stack between a UE and a BS and FIG. 7 illustrates anexample of a radio interface control plane protocol stack between a UEand a BS. The control plane refers to a path through which controlmessages used to manage call by a UE and a network are transported. Theuser plane refers to a path through which data generated in anapplication layer, for example, voice data or Internet packet data aretransported. Referring to FIG. 6, the user plane protocol stack may bedivided into Layer 1 (i.e., a PHY layer) and Layer 2. Referring to FIG.7, the control plane protocol stack may be divided into Layer 1 (i.e., aPHY layer), Layer 2, Layer 3 (e.g., an RRC layer), and a non-accessstratum (NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as anaccess stratum (AS).

In the 3GPP LTE system, the Layer 2 is split into the followingsublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 issplit into the following sublayers: MAC, RLC, PDCP and SDAP. The PHYlayer offers to the MAC sublayer transport channels, the MAC sublayeroffers to the RLC sublayer logical channels, the RLC sublayer offers tothe PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAPsublayer radio bearers. The SDAP sublayer offers to 5G core networkquality of service (QoS) flows.

In the 3GPP NR system, the main services and functions of the MACsublayer include: mapping between logical channels and transportchannels; multiplexing/de-multiplexing of MAC SDUs belonging to one ordifferent logical channels into/from transport blocks (TB) deliveredto/from the physical layer on transport channels; scheduling informationreporting; error correction through hybrid automatic repeat request(HARQ) (one HARQ entity per cell in case of carrier aggregation (CA));priority handling between UEs by means of dynamic scheduling; priorityhandling between logical channels of one UE by means of logical channelprioritization; padding. A single MAC entity may support multiplenumerologies, transmission timings and cells. Mapping restrictions inlogical channel prioritization control which numerology(ies), cell(s),and transmission timing(s) a logical channel can use.

Different kinds of data transfer services are offered by MAC. Toaccommodate different kinds of data transfer services, multiple types oflogical channels are defined, i.e., each supporting transfer of aparticular type of information. Each logical channel type is defined bywhat type of information is transferred. Logical channels are classifiedinto two groups: control channels and traffic channels. Control channelsare used for the transfer of control plane information only, and trafficchannels are used for the transfer of user plane information only.Broadcast control channel (BCCH) is a downlink logical channel forbroadcasting system control information, paging control channel (PCCH)is a downlink logical channel that transfers paging information, systeminformation change notifications and indications of ongoing publicwarning service (PWS) broadcasts, common control channel (CCCH) is alogical channel for transmitting control information between UEs andnetwork and used for UEs having no RRC connection with the network, anddedicated control channel (DCCH) is a point-to-point bi-directionallogical channel that transmits dedicated control information between aUE and the network and used by UEs having an RRC connection. Dedicatedtraffic channel (DTCH) is a point-to-point logical channel, dedicated toone UE, for the transfer of user information. A DTCH can exist in bothuplink and downlink. In downlink, the following connections betweenlogical channels and transport channels exist: BCCH can be mapped tobroadcast channel (BCH); BCCH can be mapped to downlink shared channel(DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mappedto DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped toDL-SCH. In uplink, the following connections between logical channelsand transport channels exist: CCCH can be mapped to uplink sharedchannel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mappedto UL-SCH.

The RLC sublayer supports three transmission modes: transparent mode™,unacknowledged mode (UM), and acknowledged node (AM). The RLCconfiguration is per logical channel with no dependency on numerologiesand/or transmission durations. In the 3GPP NR system, the main servicesand functions of the RLC sublayer depend on the transmission mode andinclude: transfer of upper layer PDUs; sequence numbering independent ofthe one in PDCP (UM and AM); error correction through ARQ (AM only);segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs;reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDUdiscard (AM and UM); RLC re-establishment; protocol error detection (AMonly).

In the 3GPP NR system, the main services and functions of the PDCPsublayer for the user plane include: sequence numbering; headercompression and decompression using robust header compression (ROHC);transfer of user data; reordering and duplicate detection; in-orderdelivery; PDCP PDU routing (in case of split bearers); retransmission ofPDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDUdiscard; PDCP re-establishment and data recovery for RLC AM; PDCP statusreporting for RLC AM; duplication of PDCP PDUs and duplicate discardindication to lower layers. The main services and functions of the PDCPsublayer for the control plane include: sequence numbering; ciphering,deciphering and integrity protection; transfer of control plane data;reordering and duplicate detection; in-order delivery; duplication ofPDCP PDUs and duplicate discard indication to lower layers.

In the 3GPP NR system, the main services and functions of SDAP include:mapping between a QoS flow and a data radio bearer; marking QoS flow ID(QFI) in both DL and UL packets. A single protocol entity of SDAP isconfigured for each individual PDU session.

In the 3GPP NR system, the main services and functions of the RRCsublayer include: broadcast of system information related to AS and NAS;paging initiated by 5GC or NG-RAN; establishment, maintenance andrelease of an RRC connection between the UE and NG-RAN; securityfunctions including key management; establishment, configuration,maintenance and release of signaling radio bearers (SRBs) and data radiobearers (DRBs); mobility functions (including: handover and contexttransfer, UE cell selection and reselection and control of cellselection and reselection, inter-RAT mobility); QoS managementfunctions; UE measurement reporting and control of the reporting;detection of and recovery from radio link failure; NAS message transferto/from NAS from/to UE.

FIG. 8 shows a frame structure in a 3GPP based wireless communicationsystem to which implementations of the present disclosure is applied.

The frame structure shown in FIG. 8 is purely exemplary and the numberof subframes, the number of slots, and/or the number of symbols in aframe may be variously changed. In the 3GPP based wireless communicationsystem, OFDM numerologies (e.g., subcarrier spacing (SCS), transmissiontime interval (TTI) duration) may be differently configured between aplurality of cells aggregated for one UE. For example, if a UE isconfigured with different SCSs for cells aggregated for the cell, an(absolute time) duration of a time resource (e.g., a subframe, a slot,or a TTI) including the same number of symbols may be different amongthe aggregated cells. Herein, symbols may include OFDM symbols (orCP-OFDM symbols), SC-FDMA symbols (or discrete Fouriertransform-spread-OFDM (DFT-s-OFDM) symbols).

Referring to FIG. 8, downlink and uplink transmissions are organizedinto frames. Each frame has T_(f)=10 ms duration. Each frame is dividedinto two half-frames, where each of the half-frames has 5 ms duration.Each half-frame consists of 5 subframes, where the duration T_(sf) (persubframe is 1 ms. Each subframe is divided into slots and the number ofslots in a subframe depends on a subcarrier spacing. Each slot includes14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP,each slot includes 14 OFDM symbols and, in an extended CP, each slotincludes 12 OFDM symbols. The numerology is based on exponentiallyscalable subcarrier spacing Δf=2u*15 kHz.

Table 1 shows the number of OFDM symbols per slot N^(slot) _(symb), thenumber of slots per frame N^(frame,u) _(slot), and the number of slotsper subframe N^(subframe,u) _(slot) for the normal CP, according to thesubcarrier spacing Δf=2^(u)*15 kHz.

TABLE 1 u N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

Table 2 shows the number of OFDM symbols per slot N^(slot) _(symb), thenumber of slots per frame N^(frame,u) _(slot), and the number of slotsper subframe N^(subframe,u) _(slot) for the extended CP, according tothe subcarrier spacing Δf=2^(u)*15 kHz.

TABLE 2 u N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot)2 12 40 4

A slot includes plural symbols (e.g., 14 or 12 symbols) in the timedomain. For each numerology (e.g., subcarrier spacing) and carrier, aresource grid of N^(size,u) _(grid,x)*N^(RB) _(sc) subcarriers andN^(subframe,u) _(symb) OFDM symbols is defined, starting at commonresource block (CRB) N^(start,u) _(grid) indicated by higher-layersignaling (e.g., RRC signaling), where N^(size,u) _(grid,x) is thenumber of resource blocks (RBs) in the resource grid and the subscript xis DL for downlink and UL for uplink. N^(RB) _(sc) is the number ofsubcarriers per RB. In the 3GPP based wireless communication system,N^(RB) _(sc) is 12 generally. There is one resource grid for a givenantenna port p, subcarrier spacing configuration u, and transmissiondirection (DL or UL). The carrier bandwidth N^(size,u) _(grid) forsubcarrier spacing configuration u is given by the higher-layerparameter (e.g., RRC parameter). Each element in the resource grid forthe antenna port p and the subcarrier spacing configuration u isreferred to as a resource element (RE) and one complex symbol may bemapped to each RE. Each RE in the resource grid is uniquely identifiedby an index k in the frequency domain and an index 1 representing asymbol location relative to a reference point in the time domain. In the3GPP based wireless communication system, an RB is defined by 12consecutive subcarriers in the frequency domain.

In the 3GPP NR system, RBs are classified into CRBs and physicalresource blocks (PRBs). CRBs are numbered from 0 and upwards in thefrequency domain for subcarrier spacing configuration u. The center ofsubcarrier 0 of CRB 0 for subcarrier spacing configuration u coincideswith ‘point A’ which serves as a common reference point for resourceblock grids. In the 3GPP NR system, PRBs are defined within a bandwidthpart (BWP) and numbered from 0 to N^(size) _(BWP,i)-1, where i is thenumber of the bandwidth part. The relation between the physical resourceblock n_(PRB) in the bandwidth part i and the common resource blockn_(CRB) is as follows: n_(PRB)=n_(CRB)+N^(size) _(BWP,i), where N^(size)_(BWP,i) is the common resource block where bandwidth part startsrelative to CRB 0. The BWP includes a plurality of consecutive RBs. Acarrier may include a maximum of N (e.g., 5) BWPs. A UE may beconfigured with one or more BWPs on a given component carrier. Only oneBWP among BWPs configured to the UE can active at a time. The active BWPdefines the UE's operating bandwidth within the cell's operatingbandwidth.

The NR frequency band may be defined as two types of frequency range,i.e., FR1 and FR2. The numerical value of the frequency range may bechanged. For example, the frequency ranges of the two types (FR1 andFR2) may be as shown in Table 3 below. For ease of explanation, in thefrequency ranges used in the NR system, FR1 may mean “sub 6 GHz range”,FR2 may mean “above 6 GHz range,” and may be referred to as millimeterwave (mmW).

TABLE 3 Frequency Range Corresponding designation frequency rangeSubcarrier Spacing FR1  450 MHz-6000 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

As mentioned above, the numerical value of the frequency range of the NRsystem may be changed. For example, FR1 may include a frequency band of410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 may includea frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more. Forexample, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) ormore included in FR1 may include an unlicensed band. Unlicensed bandsmay be used for a variety of purposes, for example for communication forvehicles (e.g., autonomous driving).

TABLE 4 Frequency Range Corresponding designation frequency rangeSubcarrier Spacing FR1  410 MHz-7125 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

In the present disclosure, the term “cell” may refer to a geographicarea to which one or more nodes provide a communication system, or referto radio resources. A “cell” as a geographic area may be understood ascoverage within which a node can provide service using a carrier and a“cell” as radio resources (e.g., time-frequency resources) is associatedwith bandwidth which is a frequency range configured by the carrier. The“cell” associated with the radio resources is defined by a combinationof downlink resources and uplink resources, for example, a combinationof a DL component carrier (CC) and a UL CC. The cell may be configuredby downlink resources only, or may be configured by downlink resourcesand uplink resources. Since DL coverage, which is a range within whichthe node is capable of transmitting a valid signal, and UL coverage,which is a range within which the node is capable of receiving the validsignal from the UE, depends upon a carrier carrying the signal, thecoverage of the node may be associated with coverage of the “cell” ofradio resources used by the node. Accordingly, the term “cell” may beused to represent service coverage of the node sometimes, radioresources at other times, or a range that signals using the radioresources can reach with valid strength at other times.

In CA, two or more CCs are aggregated. A UE may simultaneously receiveor transmit on one or multiple CCs depending on its capabilities. CA issupported for both contiguous and non-contiguous CCs. When CA isconfigured, the UE only has one RRC connection with the network. At RRCconnection establishment/re-establishment/handover, one serving cellprovides the NAS mobility information, and at RRC connectionre-establishment/handover, one serving cell provides the security input.This cell is referred to as the primary cell (PCell). The PCell is acell, operating on the primary frequency, in which the UE eitherperforms the initial connection establishment procedure or initiates theconnection re-establishment procedure. Depending on UE capabilities,secondary cells (SCells) can be configured to form together with thePCell a set of serving cells. An SCell is a cell providing additionalradio resources on top of special cell (SpCell). The configured set ofserving cells for a UE therefore always consists of one PCell and one ormore SCells. For dual connectivity (DC) operation, the term SpCellrefers to the PCell of the master cell group (MCG) or the primary SCell(PSCell) of the secondary cell group (SCG). An SpCell supports PUCCHtransmission and contention-based random access, and is alwaysactivated. The MCG is a group of serving cells associated with a masternode, comprised of the SpCell (PCell) and optionally one or more SCells.The SCG is the subset of serving cells associated with a secondary node,comprised of the PSCell and zero or more SCells, for a UE configuredwith DC. For a UE in RRC_CONNECTED not configured with CA/DC, there isonly one serving cell comprised of the PCell. For a UE in RRC_CONNECTEDconfigured with CA/DC, the term “serving cells” is used to denote theset of cells comprised of the SpCell(s) and all SCells. In DC, two MACentities are configured in a UE: one for the MCG and one for the SCG.

FIG. 9 shows a data flow example in the 3GPP NR system to whichimplementations of the present disclosure is applied.

Referring to FIG. 9, “RB” denotes a radio bearer, and “H” denotes aheader. Radio bearers are categorized into two groups: DRBs for userplane data and SRBs for control plane data. The MAC PDU istransmitted/received using radio resources through the PHY layer to/froman external device. The MAC PDU arrives to the PHY layer in the form ofa transport block.

In the PHY layer, the uplink transport channels UL-SCH and RACH aremapped to their physical channels physical uplink shared channel (PUSCH)and physical random access channel (PRACH), respectively, and thedownlink transport channels DL-SCH, BCH and PCH are mapped to physicaldownlink shared channel (PDSCH), physical broadcast channel (PBCH) andPDSCH, respectively. In the PHY layer, uplink control information (UCI)is mapped to physical uplink control channel (PUCCH), and downlinkcontrol information (DCI) is mapped to physical downlink control channel(PDCCH). A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCHbased on an UL grant, and a MAC PDU related to DL-SCH is transmitted bya BS via a PDSCH based on a DL assignment.

FIG. 10 shows an example of inter-gNB handover procedures to whichimplementations of the present disclosure is applied.

For inter-gNB handover, the signaling procedures consist of at least thefollowing elemental components shown in FIG. 10.

In step S1000, the source gNB initiates handover and issues a HandoverRequest over the Xn interface.

In step S1010, the target gNB performs admission control. In step S1020,the target gNB provides the RRC configuration as part of the HandoverAcknowledgement.

In step S1030, the source gNB provides the RRC configuration to the UEin the Handover Command. The Handover Command message includes at leastcell ID and all information required to access the target cell so thatthe UE can access the target cell without reading system information.For some cases, the information required for contention-based andcontention-free random access can be included in the Handover Commandmessage. The access information to the target cell may include beamspecific information, if any.

In step S1040, the UE moves the RRC connection to the target gNB. Instep S1050, the UE replies the Handover Complete.

User data can also be sent in step S1050 if the grant allows.

The handover mechanism triggered by RRC requires the UE at least toreset the MAC entity and re-establish RLC. RRC managed handovers withand without PDCP entity re-establishment are both supported. For DRBsusing RLC AM mode, PDCP can either be re-established together with asecurity key change or initiate a data recovery procedure without a keychange. For DRBs using RLC UM mode and for SRBs, PDCP can either bere-established together with a security key change or remain as it iswithout a key change.

Data forwarding, in-sequence delivery and duplication avoidance athandover can be guaranteed when the target gNB uses the same DRBconfiguration as the source gNB.

Timer based handover failure procedure is supported in NR. RRCconnection re-establishment procedure is used for recovering fromhandover failure.

The make-before-break (MBB) and RACH-less handover are considered toreduce handover interruption in LTE. For example, MBB retains the linkof source cell during handover procedure. The source cell transmits datato UE continuously until the handover is completed, so the interruptionmay be reduced. The RACH-less handover contains UL grant for handovercomplete message in mobility control information via RRC ConnectionReconfiguration message. It can help to skip the RACH procedure andreduce the interruption.

Dual active protocol stack (DAPS) based handover is considered in NR.DAPS based handover requires simultaneous connectivity with both sourceand target cell connections during the handover. This is similar to dualconnectivity (DC) feature where the UE has two connections, i.e. mastercell group (MCG), secondary cell group (SCG) as well. In case of DC, UEfallback to MCG when the SCG fails and does not trigger the RRCRe-establishment. Similarly, for DAPS based handover, as both the sourcecell and target cell connections are kept active, the UE can fallback tothe other active connection when UE detects RLF on one connection andnot trigger RRC Re-establishment. This minimizes the instances where theUE has to trigger RRC Re-establishment and thus improve the mobilityrobustness.

FIG. 11 shows an example of a protocol stack for DAPS based handover towhich implementations of the present disclosure is applied.

(1) Before handover

-   -   Only source protocol, and source key is used.

(2) Before RACH procedure (i.e., upon receiving a handover command)

-   -   Both source protocol (source key) and target protocol (target        key) exist.    -   But only source protocol, and source key is used.

FIG. 12 shows another example of a protocol stack for DAPS basedhandover to which implementations of the present disclosure is applied.

(1) During the RACH procedure

-   -   Both source protocol (source key) and target protocol (target        key) exist.    -   Source protocol, and source key is used to        reception/transmission data from source.    -   Target PHY and MAC is used to perform the RACH procedure in        target.    -   RLC is active for contention based RACH procedure.

(2) During the transmission of handover complete (i.e.,RRCConnectionReconfigurationComplete)

-   -   Both source protocol (source key) and target protocol (target        key) exist.    -   Source protocol, and source key is used to        reception/transmission data from source.    -   Target PHY, MAC and SRB PDCP is used to perform the transmission        of RRCReconfigurationComplete MCG.

FIG. 13 shows another example of a protocol stack for DAPS basedhandover to which implementations of the present disclosure is applied.

(1) After receiving random access response (RAR)

-   -   Both source protocol (source key) and target protocol (target        key) exist.    -   Source protocol, and source key is used to        reception/transmission data from source.    -   Target protocol, and target key is used to        reception/transmission data from target.

(2) After release of source

-   -   Source protocol (source key) has been deleted.    -   Only target protocol, and target key is used;

As mentioned above, in DAPS based handover, a UE which has radiocapabilities of concurrent transmissions and receptions with at leasttwo cells, may maintain connectivity with both source and target cellduring mobility to increase mobility performance.

Currently, the target node cannot properly control when the source cellconnectivity can be maintained during the mobility or even after themobility. This situation is risky in particular when the serving cellcommunication quality cannot be maintained at the expected level. Thisis because, if the communication with the source cell is maintainedlonger than necessary (e.g., when the source cell quality rapidlydegrades during mobility), the overall communication performance becomesdegraded while the target node is under-utilized for the UE.

Therefore, a method for facilitating the target node to control sourcecell connection during mobility may be required.

According to implementations of the present disclosure, the wirelessdevice may report quality of source cell (communication) to the targetcell during mobility such that target node can decide whether sourcecommunication can be continued or needs to be immediately stopped.

The following drawings are created to explain specific embodiments ofthe present disclosure. The names of the specific devices or the namesof the specific signals/messages/fields shown in the drawings areprovided by way of example, and thus the technical features of thepresent disclosure are not limited to the specific names used in thefollowing drawings.

FIG. 14 shows an example of a method for a wireless device to whichimplementations of the present disclosure is applied.

In some implementations, the wireless device may be in communicationwith at least one of a mobile device, a network, and/or autonomousvehicles other than the wireless device. The wireless device may haveradio capabilities of concurrent transmissions and receptions with atleast two cells.

In step S1400, the wireless device initiates a mobility from a sourcenode to a target node.

In some implementations, the mobility may be initiated based on amobility command received from the source node, i.e., current basestation of the wireless device. The mobility command may requiremobility from the current serving cell, i.e., source cell, to a targetcell. The mobility command may require mobility from one or more servingcells to one or more target cells. That is, CA/DC operation at thesource node may be kept for DAPS handover, and CA/DC operation at thetarget node may be configured for DAPS handover.

In some implementations, initiating the mobility may comprise attemptingan access to the target node. For example, initiating the mobility maycomprise initiating random access to the target cell to establishconnection with the target cell.

In step S1410, the wireless device keeps communicating with the sourcenode.

In some implementations, the wireless device may keep transmissionand/or reception of data to/from the source cell while attempting theaccess to the target cell. That is, a communication with the source nodemay be kept while attempting the access to the target node.

In some implementations, the wireless device may keep measuringcommunication quality of the source node while attempting the access tothe target cell. The communication quality of the source node may bedefined by at least one of the followings.

-   -   The communication quality of the source node may include radio        quality of at least one cell at the source node. The        communication quality of the source node may include radio        quality of a PCell at the source node. The communication quality        of the source node may include radio quality of at least one        SCell at the source node. The communication quality of the        source node may include radio quality of both PCell and        available SCell(s) that are configured to keep operating during        DAPS handover at the source node. In case the wireless device        has been configured with DC at the source node, the        communication quality of the source node may include radio        quality of at least one of MCG and/or SCG.    -   The communication quality of the source node may include radio        quality obtained by radio resource management (RRM)        measurements, such as reference signal received power (RSRP),        reference signal received quality (RSRQ) and/or signal to        interference plus noise ratio (SINR).    -   The communication quality of the source node may include layer 1        channel quality information, such as channel quality indicator        (CQI) based on channel state information reference signal        (CSI-RS) measurement and/or a synchronization signal        (SS)/physical broadcast channel (PBCH) block measurement.    -   The communication quality of the source node may include layer 3        (e.g., RRC layer) filtered results of the layer 1 channel        quality information. The filtering by the layer 3 may be based        on exponential weighted moving average.    -   The communication quality of the source node may include        expected performance of communication between the source cell        and the wireless device, such as expected data rate, expected        packet delay over the source cell, etc. For example, the        expected performance may include estimated performance during        the mobility (e.g., while attempting the access to the target        cell). For example, the expected performance may include average        performance calculated until the mobility is completed.

In step S1420, the wireless device transmits, to the target node,information related to a communication quality of the source node.

In some implementations, while attempting the access to the target cell,the wireless device may transmit to the target cell a message includingthe information related to the communication quality of the source node.The message may indicate that the access to the target cell issuccessful, e.g., RRC(Connection)ReconfigurationComplete message. Or,the message may indicate success of the mobility.

In some implementations, the information related to the communicationquality of the source node may be included as information element (IE)in the message. Or, the information related to the communication qualityof the source node may be included as MAC control element (CE) in themessage.

In some implementations, the information related to the communicationquality of the source node may be indicated by layer 1 signaling.

In some implementations, upon receiving the information related to thecommunication quality of the source node from the wireless device, thetarget node may decide whether to allow the source node to keepcommunication with the wireless device for some time defined by criteriaor to request the source node to stop communication with the wirelessdevice. Such decision may be based on policy of the target node and/orthe information related to the communication quality of the source nodereceived from the wireless device in step S1420.

For example, if the communication quality of the source node is below athreshold, the target node may decide that the source node is requiredto immediately stop communication with the wireless device. In thiscase, following operations may be as follows.

(1) The target node may request the source node to stop communicationwith the wireless device by sending an inter-node message including therequest to the source node.

(2) Upon receiving the inter-node message including the request to stopcommunication with the wireless device, the source node may immediatelystop communication with the wireless device. The source node may performat least one of the followings.

-   -   The source node may start forwarding of packets that are        buffered but transmitted yet or transmitted but unacknowledged        along with sequence number (SN) transfer procedure.    -   The source node may initiate path switching procedure towards        the gateway (e.g., user plane function (UPF)) to change data        path from the source node to the target node.    -   The source node may send a message to the wireless device to        request release of the source cell (i.e., termination of        communication with the source cell).

(3) Upon receiving the message to release a communication with thesource node, the wireless device may release the communication with thesource node.

For another example, if the communication quality of the source node isabove a threshold, the target node may decide that the source node isallowed to keep communication with the wireless device until a criteriais satisfied. In this case, following operations may be as follows.

(1) The target node may allow the source node to keep communication withthe wireless device until a criteria is satisfied, by sending aninter-node message to the source node.

In some implementations, the inter-node message may include informationthat specifies the criteria. The criteria may be defined by one of thefollowings.

-   -   Criteria 1: Maximum time duration for which the source node can        maintain communication with the wireless device.    -   Criteria 2: Information only allowing the source node to send        the packet that are buffered but transmitted yet or that are        transmitted but unacknowledged. This information may mean that        any new incoming packet from core network (e.g., gateway) after        the reception of the inter-node message needs to be forwarded to        the target node.    -   If the criteria 1 and the criteria 2 are jointly included in the        inter-node message, either criteria whichever satisfied earlier        may require the source node to stop communication with the        wireless device.

(2) Upon receiving the inter-node message including information thatallows the source node to keep communication with the wireless deviceand/or information that specifies the criteria from the target node, thesource node may keep communication with the wireless device. The sourcenode may keep communication with the wireless device until the criteriamentioned above is satisfied. If the criteria is satisfied, the sourcenode may perform at least one of the followings.

-   -   The source node may start forwarding of packets that are        buffered but transmitted yet or transmitted but unacknowledged        along with sequence number (SN) transfer procedure.    -   The source node may initiate path switching procedure towards        the gateway (e.g., UPF) to change data path from the source node        to the target node for the data flow anchored at the gateway.    -   The source node may send a message to the wireless device to        request release of the source cell (i.e., termination of        communication with the source cell).

(3) Upon receiving the message to release a communication with thesource node, the wireless device may release the communication with thesource node.

The present disclosure can have various advantageous effects.

For example, upon receiving information related to the communicationquality of the source node and/or source cell from the wireless device,the target node can decide whether to allow the source node keepscommunication with the wireless device or to request stoppingimmediately communication with the wireless device.

For example, the target node can properly control source cellconnectivity during and/or after mobility.

For example, overall communication performance can be enhanced while thetarget node is properly utilized for the wireless device.

Advantageous effects which can be obtained through specific embodimentsof the present disclosure are not limited to the advantageous effectslisted above. For example, there may be a variety of technical effectsthat a person having ordinary skill in the related art can understandand/or derive from the present disclosure. Accordingly, the specificeffects of the present disclosure are not limited to those explicitlydescribed herein, but may include various effects that may be understoodor derived from the technical features of the present disclosure.

Claims in the present disclosure can be combined in a various way. Forinstance, technical features in method claims of the present disclosurecan be combined to be implemented or performed in an apparatus, andtechnical features in apparatus claims can be combined to be implementedor performed in a method. Further, technical features in method claim(s)and apparatus claim(s) can be combined to be implemented or performed inan apparatus. Further, technical features in method claim(s) andapparatus claim(s) can be combined to be implemented or performed in amethod. Other implementations are within the scope of the followingclaims.

What is claimed is:
 1. A method for a wireless device in a wirelesscommunication system, the method comprising: initiating a mobility froma source node to a target node; keeping communicating with the sourcenode; and transmitting, to the target node, information related to acommunication quality of the source node.
 2. The method of claim 1,further comprising receiving a message to release a communication withthe source node.
 3. The method of claim 2, further comprising, uponreceiving the message, releasing the communication with the source node.4. The method of claim 1, wherein the communication quality of thesource node corresponds to radio resource management (RRM) measurementsincluding at least one of a reference signal received power (RSRP), areference signal received quality (RSRQ) and/or a signal to interferenceplus noise ratio (SINR).
 5. The method of claim 1, wherein thecommunication quality of the source node corresponds to layer 1 channelquality information including at least one of a channel stateinformation reference signal (CSI-RS) measurement and/or asynchronization signal (SS)/physical broadcast channel (PBCH) blockmeasurement.
 6. The method of claim 5, wherein the communication qualityof the source node corresponds to layer 3 filtered results of the layer1 channel quality information.
 7. The method of claim 1, wherein thecommunication quality of the source node corresponds to an expectedperformance of communication between the source node and the wirelessdevice including at least one of an expected data rate, an expectedpacket delay over the source node.
 8. The method of claim 1, wherein theinformation related to the communication quality of the source node istransmitted via a message indicating that the mobility to the targetnode is successful.
 9. The method of claim 8, wherein the message is aradio resource control (RRC) reconfiguration complete message.
 10. Themethod of claim 1, wherein the mobility is initiated based on a mobilitycommand received from the source node.
 11. The method of claim 1,wherein initiating the mobility comprises attempting an access to thetarget node.
 12. The method of claim 11, wherein a communication withthe source node is kept while attempting the access to the target node.13. The method of claim 11, wherein the communication quality of thesource node is measured while attempting the access to the target node.14. The method of claim 1, wherein the wireless device is incommunication with at least one of a mobile device, a network, and/orautonomous vehicles other than the wireless device.
 15. A wirelessdevice in a wireless communication system, the wireless devicecomprising: at least one transceiver; at least processor; and at leastone computer memory operably connectable to the at least one processorand storing instructions that, based on being executed by the at leastone processor, perform operations comprising: initiating a mobility froma source node to a target node; keeping communicating with the sourcenode; and transmitting, to the target node, information related to acommunication quality of the source node.
 16. A wireless device in awireless communication system, the wireless device comprising: at leastone memory; and at least processor, operably coupled to the at least onememory, wherein the at least one processor is configured to: initiate amobility from a source node to a target node; keep communicating withthe source node; and generate, to the target node, information relatedto a communication quality of the source node.